The present invention relates generally to tubular or sleeve style cartons used in the packaging of beverage containers such as aluminum cans. More particularly, the invention relates to an alignment means for the flaps used to close the ends of the tubular carton.
Tubular beverage cartons have been known for many years. An example is shown in U.S. Pat. No. 4,508,258, wherein a tubular carton includes top, bottom and side panels. At each end of the carton, dust flaps which partially close the carton end are connected along fold lines to the top and bottom panels. End closure panels are connected to the side panels and extend substantially the full height of the carton to close the carton end.
In order to improve the folding operation in closing the carton ends, it is common practice to remove some of the carton material along the side edges of the dust flaps and/or end flaps. In fact, U.S. Pat. No. 4,508,258 teaches the removal of greater material than normal in order to further enhance folding performance. At the same time, a problem exists in folding the end flaps in that, for various reasons including drag on the carton as it moves through erecting and loading machinery, the carton can become slightly skewed during the folding operation. Gluing of the flaps into a closed position then maintains the carton in an unwanted skewed condition.
The referenced U.S. Pat. No. 4,508,258 teaches that the removal of carton material from the upper and lower side edges of the end flaps will permit some degree of misalignment to occur without affecting the closing of the carton. However, such misalignment is still objectionable from an appearance standpoint, particularly where printing on the carton end requires text or graphic images which extend over the end flaps.
What is needed is an end-closure structure for a tubular beverage carton in which excess material does not interfere with the folding operation of the carton, but yet provides means for maintaining the carton in rectangular alignment.